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I o. c. TRAVER May 15, 1928. siflcfinomzmq nsvxcz Re 6 2 Sheets-Sheet 1 Original Filed July 29, 1922 lnVn-bori Oliver" C. Traver;

His fitter-neg.

v y o. c. TRAVER I May 15, T928.- smcnnouxzmn DEVICE I R 16,966

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Relaaued May 15,

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Original Io. 1,508,120, (lat ed I ovember 24, 1925, Serial No. 578,475, flied July 29, 1922. main Io.

10,540, dated February 8, 1927,

Serial No. 158,040, filed December 6, 1926.. This application for,

release fled Iovember 21, 1927. Serial 170. 804,878.

M invention relates to improvements in sync iron'izing devices and has for an ob ect to provide an improved synchronizing dc,-

- vice for automatically controlling the opera 5 tion of connecting an alternatin current dynamo electric machine to an a ternating current electric circuitwhereby the connection can bemade substantially only at the instant when the electromotive forces of the 1 machine and circuit are alike infrequency,

phase and value.

My invention will be better understood 3 from the following description taken in con-.

nection with the accompanying drawing, and its scope will be pointed out in the appended claims.

Figure 1 illustrates diagrammatically an embodiment of my invention, and Figs. 2 to 11, inclusive,are vector dia trating the (principles upon whic my invention is base For purposes of illustration,I have shown in-Fig.1 an embodiment of my invention as applied to a three phase alternatingcurrent e ectric s stem comprising an alternating current e ectric circuit such as a bus 1 to which may be connected one ormore d namo electric machines 2 or sources of a ternating current in parallel as is well known to the art. I have illustrated the d namo electric machine 2 as an alternator a apted to be connected to the bus 1 by any suitable circuit controllin means 3 arranged to control a circuit 4 etween the bus 1 and the alternator 2. The circuit controlling means 3 preferab1y comprises an electroresponsive closing means such as a closin coil 5 connected in a control circuit 6 w ich ma be connected across a control bus 7', and w ich ma include an auxiliary switch Sarranged to e controlled by the circuit controlling means 3 so as to be closed when the circuit controlling means is open and open when the circuit controlling means is closed.

For controlling the control circuit 6, I

provide elec-troresponsive means comprising.

- a pluarlity of circuit-controlling members 9,10 and 11 which are arranged to control contacts 12, 13 and '14 or'15, respectively,

arranged 'in series in the control circuit 6.

V The electroresponsive means may comprise a plurality of differentially actin electroresponsive devices or relays 18-, 1 and 18 ems illus-.

force on the which may be of the shaded pole induction disk motor type, each element comprising an induction disk and. a plurality of motor ele-- ments arranged to exert opposing torques thereon.

For energizing the. motor elements of the relays I provide, in accordance with my invention, a plurality of sources of electromotive force such as potential transformers tive forces are in phase.

The relay 16 which controls circuit con-' 'trollingmember 9 may comprise an induction disk 23, shaded pole motor elements 24 and 25 arranged ,to exert opposing torques thereon, an suitable means suchas a drag magnet 26 for exerting a retarding disk 23 so as to obtain a. time delay action in the movement thereof. Movement of the disk 23 in a direction to carry circuit controlling member 9 away from-circuit closing position is limited by any suitable means such as a stop 26. The position of the stop 26' relatively to the contacts 12 may be determined in accordance with the angular movement of the disk 23 necessary to provide the time delay desired and in a practical embodiment of my invention I have arranged the stop 26 and the contacts 12 so that the disk 23 may have an angular movement of approximately 180. Motor element 24 is provided with an energizing winding 27 connected in series relation with 25 is provided with an energizin winding 28 connected inseries relation wit the secondaries of the potential transformers 20- trolling member 10 may comprise an induc- V the secondaries of the potential, transformers 19 and 21 and motor element tion' disk 29 and shaded pole motor elements 30 and 31 arranged to exert opposing I torques thereon. Motor element 30 is provided with an energizing winding 32 con-- nected in series relation with the secondaries of the transformers 19 and 21, and motor "element 31 is provided with an energizing winding 33 connected in series relation with the'secondaries of the transformers and 22. The motor elements and 31 tend to disk 29 is so shaped and the shaded poles of the motor elements 30 and 31 so arranged with respect to the disk 29 that in the event I of either of the. motor elements 30, 31 predominating to turn the disk" 29, the torque -a snap action which is desirable.

exerted by the stronger element is increased while the torque exerted by the Weaker element is decreased. One way to obtain this efiect is to remove a segment of the disk 29 and arrange the shaded poles as shown so that an increasing'area of the disk is presentedadjacent the shaded pole faces of. the motor element tending to exert the greater torque and a decreasing area of the disk adjacent the shaded pole faces of the motor element tending to exert the smaller torque. This construction and arrangement of parts also provides for a quick ositive movement of the disk 29 substantial y of the'nature of Moveinent of the disk 29 in a direction to carry circuit controlling member 10 awa from circuit closing position is limited y any suitable means such as a stop 34.

The relay 18 which controls circuit controlling member 11 ma comprise an induc-v tion disk 35 and shade pole motor elements 36 and 37 arranged to exert opposing torques thereon. The motor element 36 is provided with an energizing winding 38 connected across the terminals of the secondary of transformer 21 and the motor element 37 is provided with an energizing winding 39 connected across the terminals of the secondary of the transformer 19. The motor elements 36 and 37 tend to exert opposing torques on the disk 35 irrespective of the directions of current flow in their windin s 38 and 39 respectively. Obviously when t e motor elements 36 and 37 exert equal tor ues, that is to say, when the voltage of the a ternator 2 is substantially equal to the volta e on the bus 1, the disk 35 will tend to remain stationary and the contacts 14 and 15 closed, but upon the occurrence of a predetermined diflerence in these voltages, the disk 35 will beturned in one directlon or the other to openeither contacts Her 15. One of the contacts of each of the pairs of contacts 14 and 15. maybe provided with a. depending or tail portion 40 extending into t e path of movement of the circuit c0nt1'o11ing -voltagem.

vice; it willbe desirable to refer to Figs. 2

to 11. inclusive, which are vector diagrams illustrating the prineiples'npon which my' invention isbasetl. I In these diagrams, the heavy solid lines designated I) and shown in a fixed position as a reference line. represent the voltage on the bus 1 or a voltage proportional thereto 'as, for example, the voltage across the secondary of each of the transformers 19 and 20. he heavy solid lines designated 2 represent the voltage of the alternator 2 or 'a voltage proportional thereto as. for example, the voltage across the secondary of each of .the transformers 21 and 22. The vector e is assumed to rotate in accordance with the phase relation of the two electromotive forces to be synchronized.-

The heavy dashed lines designated a, repre sent the voltage a reversed. The vectors E,-

e and a, are assumed equal in length as. this is a condition for controlling the control circuit 6 under the control of relay element 18 or other equivalent means. The light solid lines designated a: and 37 represent the vectorial difierences of E and e, and E and e respectively, that is to say, a: represents the vectorial difl'erence and y the vectorial sum of E and e. The voltages a: and y, inaccordance with their relative values control the o eration of the relay elements 16 and 17. orconvenience, the vector diagrams are assumed to be divided into four" quadrants a, b, a, and d respectively as indi cated in Fig. 10. Fig. 2 represents the in-phase, condition of the voltages on the bus 1 and the alternator. 2. In this case the vectors E and e coincide, a: is zero and 31 has its maximum,

value.

nator less t an degrees out of phase withthe voltage on the bus 1, that is to say voltage is quadrant a. In this case, voltage 3 isgreater than'voltage z.

Fig.4 represents the voltage. of the alters nator 2, 90 de rees out'of phase with thevoltage on the, us 1. In this case, voltage 0: equals voltage 3 Fig. 5 represents the voltage of the alter- 7 6 Fig. 3 re resents the voltage of the alter- 1 attainedquadrants b and 270 degrees out of phase iegeee Fig. 6 represents the voltage of the alter nator 2,180 degrees out of phase with the voltage on the bus 1. In this case :c'has 'ts maximum value and 3 is zero.

Fig. 7 represents the voltage of the alternator 2 more than 180 degrees and less than with the voltage on the bus 1, that is to say, voltage e in quadrant 0. In this case voltage a: is greater than voltage y.

Fig. 8 represents the voltage of the alternator 2", 270.degrees out of phase with the In this case, voltage phase coincidence where voltage 3 has a voltage on the bus 1. w e uals voltage y.

Fig. 9 represents the voltage of the alternatorg2, more than 270 degrecsand less than 360' degrees out of hasc withthe voltage on the bus 1, that is to say, voltage e n quadrant d apaproaching pliasccoincidence with voltage In. this case voltage y is greater than voltage 41;.

tive values of the voltages w and y'inthe difi'erent quadrants and under the diflei'ent conditions heretofore considered. From these figures, particularly Fig. 10, and assuming disk 23 notretarded in its movement and disk 29 circular and motor difierence, viz, 90 degrees to 270 degrees or when voltage y is less than voltage 0:, as in 0, motor elements 24 and i would. predominate to turn their respecdisk tive disks-counter clockwise, that is, the

disk

23 to circuit opening position and the 29 to circuit closing position through another certain range of ference, viz, 270 degrees to base dif-v egrees or when voltage y is greater than voltage w,

as in quadrants d and a, motor elements 25 and 31 would predominate 'to turn their disks 23 and 29 clockwise, that is, 'disk 23 to circuit closing position and disk 29 to circuit 0 nin position. Under these conditions t e dis s 23 and 29 would not simultaneously be in circuit closing position.

In order that the circuit controlling means 3 may be closed only when the electromotive forces of the bus 1 and stantially alike in phase,

frequency and value 7 I so construct and arran e the relays and 18 that. the move le elements thereof must simultaneously be in 'predeter minedpositions. For this purpose; I may construct the respective motor elements of relays 16 and 17 of different strengths. and provide means for retarding the movement of the disk'23 and also arrange the disks 29 to provide diiferential effects.

elements 36 and 37 of relay 18 may be substantially the I same values :12, and

.predominate and move disk 23 to circuit -Fig. 10 is a summary indicating the rela andthattion e5, voltage :1:

alternator 2 are sub The, motor similar in construction so as to permit the contacts 14 and 15 to remain closed when the difference in'voltages of alternator 2 and bus 1 is within a predetermined amount which in a practical embodiment of my invention, I have taken so that the voltages must be within five per cent of each other.

Referring now to element 25 maybe so constructed as to predominate over motor element 24 tostart disk Figures 1 and 11, motor 23'moving to circuit closing position when voltage e has reached a position 0, prior to value 3 and voltage a: the correspondin value x, and contacts 12 will be closed wit a time delay, and

where a and 3 again have substantially the motor element 24 will opening position. In a practical embodiment of my invention vo tages m and 3 have substantially the values 40 and 220 volts respectively. Thus,.as voltage 6 moves when" voltage e' passes through phase coincidence to a position a,

to and away from phase coincidence through the range of phase dilference from 6 to e,,' disk 23 will be moved toward circuit'elosing position with atime dela while in the range of phase difierence rom a through. phase opposition to 8 toward circuit. opening position. For the values ofthe voltages a; and y and the action herein set forth, it will be obvious that motor element 24 shout o. he constructed to' exert the predominant torque when voltage a: is greater than 40 volts and voltage y less than 220 volts. In which case motor element 25 will exert the predominant torque when voltage a: is less than .40 volts and voltage 3] greater than 220 volts. x i y The position a, of the voltage e, 'Fig. 11 corresponds to the parts in Fig. 1. In this position, more of the disk 29 is adjacent the pole faces of motor element 30 than is ad acent the pole faces of motor element 31. Motor element 30 then predom nates to hold disk 29in circuit clos ing' position. As volta e e moves to sub stantially phase coinci ence, that is, posidecreases to ac,- and voltage and motor element 31 then y increases to y, predominates to move disk 29 quickly to circuit opening position. According to my in- I vention, the particular position of c, is prefat' l disk 23 will be moved in position as shown erabl'y, for r'actical purposes, just before hase coinci ence .as this allows somewhat. or the time necessar -to close the circuit controlling means 3. -In a practical"embodiment of my invention, motor element 31 is constructed to predominate when volt-ages w and y reach substantiallvythe values'20 and 220 volts respectively. When. motor ele ment -31 predominates to move the disk 29 clockwise, an increasing area of the disk 29 will be presented adjaccntits pole faces 7 and a decreasing area. add'accnt the pole faces of motor element 30. onsequently, motor element 31 will be rendered more effective in its predominance and the effect of motor element 30 decreased. The disk 29 will therefore he quickly moved to circuit opening position and more of the-disk 29 will be ad- Jacent the pole faces of motor element 31 and less at jacent the pole faces of motor element 30. Consequently voltage a: will have to increase appreciably and voltage y decrease accordin ly in order that motor element 30 may prcc ominate to move the disk 29 to circuit clo ing position. In order-toj insure that the disk 29 may not move to circuit closing position until after the d sk 23 has moved to circuit opening position, I c'onstruct the motor elements '30 and 31 so that with the disk 29 in circuit openingposition, the voltage a must reach a position 5,. ua

' cuit closing position. The 'particularposition of e, is immaterial, the main requisite being that the position of e' where motor element 30 predominates to move disk 29 to circuit closing position should be in phasedisplacement subsequent to the position e,

where motor element 24 predominates I to move the disk 23 to circuit opening posi tion. .In a practical embodiment of myinvention, the values of the voltages at and y,

corresponding to thesposition e -of the voltage e, are each substantially 150 volts. When motor element 30 predominates to move the disk 29 to circuit closing position, the disk (see Fig. 1) will remam substantially .in

this position until voltage e reaches the position a when motor element 31'will again predominate and move the disk 29 to circuit openin position as heretofore set forth.

Thus, as vo tage 0 moves to and away from phase coincidence through the ran e of. phase difierence from e to e the disk 29 will be in circuit opening position while in the range of phase difference from e throu h phase opposition to e the disk 29 will be in circuit closing position. It will therefore be obvious that the difference between the frequencies of the alternator and bus voltages must be less than a predetermined amount in order that the disk -o ening 23 may have time to'move to circuit closing position before disk 29 is moved to circuit osition. Moreover, the range of.

p a'se di erence over which both the disks 23 and 29 may simultaneously ,be in circuit closing position is limited and consequently the control circuit 6 can be completed onlyduring a limited number of de 'synchronism' and not after.

recs before rum frequency, and value. from Fig. 11 and the explanation therewith switch closing somewhat for the time required to close the circuit controlling means 3. It is, of course,

ternator voltage has the same 1 requencly as, and is in phase with, the bus voltage is therefore clear that the control circuit 6 controlling the operation of closing the circuit controlling means 3 can be closedonly when the voltages of the alternator 2 and the bus 1 are substantially alike in phase, It is .moreover clear that contacts 13 which open 'ust before synchronism remain open until degrees or more after synchronism since motor element '.3l of. relay-17 tends to predominate until the voltage e is substan grees beyond phase coincidence. Although I have shownand' described my invention in considerable detail, I do not wish to be limited to the s ific. details thereof, as shown and descri d, but may use such modifications, substitutions or equivalents thereof, as are embraced within the spirit-of my invention.

-What I claim as new and desire to secure by Letters Patents 'f the-United States is:

1. In a system f the class described wherein two. sources of alternating electially- 90 detromotive force are ,to be synchron1zed,a

switch for connecting the sources, and means for controlling the closing of said switch, comprising a plurality of relays connected and arranged so that the movable elements of the res ective' relays must simultaneously be in pred switch to be closed, one of'said relays being connected to said sources of electromotive force and arranged to tend to move to osition during a predetermined range 0 the electromotive forces near phase 00-incidence and tending to move away from switch closing position when the phase difference is outside of this range, means for delaying the operation of said relay whereby it can reach switch closing position during the predetermined range of phase dif ference only when the frequencies of said electromotive forces are. substantially the" same, another of saidrelays'being connect- .ed to'said sources of electromotivc force then move quic y out of switch closing etermined positions to enable said phase difference between Ill lab

' closing means adapted to be operated to connect said sources, and means for 'eifrectin the operation of said connecting means wfien the electromotive forces of said sources are in synchronism, comprising a control circuit, a plurality of contacts arranged in series in said control circuit and a plurality of relays-for controlling said contacts having energizing windings connected in circuit with said sources to render said rela 5 re-' sponsive to the phase relatlon of sa1 elec tromotive forces, one" of said relays beln o rative in response to a predetermine ase difference between said electromotive ibrces to close the contacts controlled there-- by'and upon the occurrence of a smaller predetermined hase difference to open said contacts an another of said relays being 0 erative in res onse to a predetermine p ase difference orces with a time delay such that the contilCtSCOl'llZl'OllGd thereby are moved to circuit sition while said first contacts are in circuit closing osition only when the difference between t e frequencies of said electromotive forces is below a predetermined value.

3. In a system of the class described wherein'two sources of alternating e1ec tro motive force are to be synchronized, a switch for connecting the sources together and means for controlling the closing of said switch, comprising a dplurality of relays connected and arrange so that the movable elements of the respective relays must simultaneously be in redetermined positions to enable said switc said rela s each having windings connected to be in ividually responsive to a resultant of the instantaneous values ofthe electromotive forces to be synchronized, one of the windings on each relay being arranged to tend to move the element of the relay oppositely to the tendency of another winding to move the element so that movement of the element of each of said relays depends upon the differential effects of the winding thereon, the windings on eachrelay being. connected so that when the electromotive forces are in phase one winding approaches its maximum effect and the other winding its minimum effect, one of said relays being arranged to tend to close while said electromotive forces are within a predetermined ran of phase difference, means for retar ing the operation of said relay so that the element thereof can reach circuit closing tween said electromotive to be closed, two of position only when the fre uencies' of the electromotive forces are su stantially the same, the other relay being constructed to remain 'closedduring a predetermined range of phase difference while said electromotive forces are approaching phase coinci dence and to move quickly away from switch closing position when the electromotive forces are substantially in phase whereby the switch can be closed only when the frequencies of, the electromotive forces are so nearly the same as to permit synchronizingand only during an interval w ile the electromotive forces are approaching phase coincidence and their phase difference is within a predetermined range. a

4. Inan alternating current electric system wherein the electromotive force of an alternating current dynamo electric machine is to be synchronized with the electromotive force of an alternating current electric cir cuit, synchronizing means comprising aplurality of cooperating electroresponsive devices, one of said devices comprising a movable memher, contacts controlled by the movement thereof, and a plurality of motor elements arranged to exert opposing torques on said member, one of'said elements being connected in circuit to be energized in accordan ce with the vectorial sum of and another in accordance with the vectorial di rence between said electromotive forces, he construction and arrangement of parts bein such that said elements operate tovmove said member to contact closing position upon the occurrence of a (predetermined hase difference between sai electromotiye orces and tomove said member from contact closing position upon the occurrence of a smaller predetermined phase diiference, and another of said devices comprising a movable member, contacts controlled by the movement thereof, means for retarding the movement of said member, and a plurality of motor elements arranged to exert opposing torques connected in circuit to be energized in accordance with the vectorial sum of and another inaccordance with the vectorial difference between said electromotive forces whereby movement of said member to contact closin position is effected in accordance with the guise difference between said elec-i tromotive forces, the construction and artern wherein two sources of alternating electromotive force are to be synchronized, means for connecting the sources, and means no on said member, one of said elements being s for controlling the closin of said connect-,

ing means comprising'a urality of cooperatlng electroresponsive evlces, each of said devices comprising a movable member and having energizing windings arranged to exert opposing effects thereon, the energizing windings of each of two of said devices belng connected in clrcult with said sources to be energized respectively in accordance with the sum of and difference between the instantaneous values of the electromotive 'forces to render the .devices operative in response to the phase relation thereof, the movable member of one of said two devices being operative in response toa predetermined phase difference between said electromotive forces to move to circuit closing position and to move to circuit opening position in response to a smaller predetermined shase difference and the other of said two evices comprising means for retarding the movement of the movable member thereof whereby the member is operative in response to a, redetermined phase differencebetween .the e ectromotive forces to move to circuitclosing position with a time delay such that when the difference between the frequencies of said electromotive forces exceeds a pre determined amount c1rcu1t closing pos tion ly be inv predetermined positions to enable said connecting means to be closed. I

6. In an alternating current electric system wherein two sources of alternating electromotive force are to be synchronized, synchronizing means comprising a control cir cuit and a plurality o cooperating electroresponsive devices for controlling said cir-' cuit, one of said devices comprising a rotatable contactcontrollingmember and a plurality of motor elements arranged to'exert opposing torques thereon connected in circuit with said sources to be energized in accordance with the vectorial sum of and difference between the electromotive forces thereof respectively, the construction and arrangement of parts being such that upon the occurrence of a predetermined hase differencebetween the electromotive orces said member 18 (quickly moved to circuit closing position an upon the occurrence of a smallor predeterminedphase difference is quickly nane moved to circuit opening position, another of said devices comprising arotatable contact controlling member, means for retarding the movement thereof and a plurality currence of predetermined phase difference between the electromotive forces sald mem-' her is moved to circuit closing position with a time delay such that when the difference between the fre uencies of said electromotive forces excee s a redetermined amount said member will tend to reach circuit closing position subsequently to the movement of said first member to circuit opening position.

7.In an alternating current electric system wherein two sources of alternating electromotive force are to be synchronized, means adapted to be 0 erated to connect said sources, and means or effecting the operation of said connecting means when the electromotive forces of said sources are substantially equal and in synchronism, comprising acontrol circuit,,a plurality of relatively movable cooperating contacts arranged-in series in said control circuit and a plurality of relays for controlling said contacts, two of said relays'having energizing windings connected in circuit with said sources to render said relays responsive to the phase relation of the electromotive forces IUU thereof, one of said two relays being operative in response to a predetermined phase difference between, the electromotive forces to close the contacts controlledthereby and hold them closed until the occurrence of a smaller predetermined phase difference be ofsaid two relays being operative in re sponse to a redetermined phase difference between said electromotive forces with a timedelay such that the contacts controlled 'thereby aremoved'to circuit closing posiresponse to the difference between said electromotive forces whereby the contacts controlled thereby are moved to circuit opening position u on the occurrence of a predetermined di erence between said electromotive forces. a v

8. In an alternating-current electric system wherein two sources of alternatingeleclllh tween sald electromotive forces, andanother III 1 currents in the energizing and each of said devices laced tromotive force are to be synchronized, means for connecting said sources,- means] comprising a control circuit for effecting the operation of said connecting means, and means for controlling said control circuit comprising a plurality of electroresponsive devices each including a rotatable member, contacts-controlled thereby and arranged in series in said control circuit and 'a plurality of motor elements constructed and arranged to exert opposing torques on said rotatable member irrespective of the directions of the aving the energizing winding of one of the motor elements connected in circuit to be energized in accordance with the sum of the electromotive forces of said machine and said circuit and the energizing winding of another of said elements connected in circuit to be energized in accordance with the difference between said electromotive forces whereby said devices are responsive to the phase difference and difference between the frequencies of said electromotive forces, the rotatable member of one of said devices being adapted upon movement thereof in response to the occurrence of a difference between the torques exerted thereon by said motor elements to increase the effect of the element exerting the greater torque and decrease the effect of the element exerting the smaller torque whereby the predominant motor element is rendered more effective, the construction andarrangement of parts being such that said motor elements operate to move said member to contact controlling position upon the occurrence of a predetermined phase difference and to hold said member in contact closing position until the occurrence of a smaller predetermined phase difference, and another of said devices comprising means for retarding the movement of the rotatable member thereof, the con- .struction and arrangement of parts being such that when the difference between the frequencies of said electromotive forces is below a predetermined value said rotatable member is caused to move tocontact closing position while the contacts of said first device are closed whereby said control circuit is completed to effect the closing of sald connecting means.

9. 'In combination, two alternating current circuits, switching means for connecting the circuits, and means controlled in accordance with the phase relation and the difference between the frequencies of the electromotive forces of the circuits for starting the closing operation of the switching means only when the phase difference of the electromotive forces exceeds a predetermined value and the difference between the frequencies of the electromotive forces is less than a predetermined value.

windings thereof,

10. In combination, two alternating current circuits, switching means for connecting the circuits andmeans connected'to be energized in accordance with the difference between the effects of the sum of and the difference between the electromotive forces of the circuits for starting the closing oper- I,

ation of the switching means only when the phase difference of the electromotive forces exceeds a predetermined value and the difference between the frequencies of the elecbetween the electromotive forces of the circuits when the difference between the frequencles is less than a predetermlnedvalue, and a relay responslve to conditions in said circuits operable within said range to control another connection in the control circuit.

12. In combination, tw'o alternating cur rent circuits, means for bontrolling the in tel-connection of .said circuits comprising a control circuit, a relay connected and arranged to be energized in accordance with the sum of and the difference between the electromotive forces of the circuits operable to make a connection in the control circuit onl during a predetermined range of base di erence between the electromotive orces when the frequency difference between the electromotive forces is less than a redetermined value,.and a relay connectefiand arranged to be energized in accordance with the sum or and the difference between the electromotive forces operable within said range to control another connection in the control circuit.

13. In combination, two alternating current circuits, a switch for connecting the circuits, and means for controlling the closing of the switch comprising a p u relays connected and, arranged so that the movable elements thereof must simultaneous- 1y be in predetermined positions to start the closingoperation of the switch, one of said relays be1ng connected "to said circuits and arranged to tend to move to switch closing position during a predetermined range of phase difference between the electromotive forces of the circuits and to move from switch closing position when the phase difference is outside this range, means for delaying the operation of said relay whereby the relay can reach switch closing position only vhen the difference between the frequencies of the electromotive forces is less than a predetermined value, and another of said relays being connected to said circuits rality of v Ill) 8 a and arrangedtoremaininswitch closing 'tion during a range of phase difference a; to the end of said nning sub uentl first'range of ghase difference and ending prior to phase coincidenceand then to move quickl out of switch closing position;

14. combination, two alternating current circuits, a switch for connecting the cir .cuits, and means for controlling the closing ofthe switchcomprising a pluralit of relays connected and arranged-SO that t e movable elements thereof must simultaneously be in predetermined positions to start 'the closing operation of the switch, one of said relays being connected to said circuits and arranged-to tend to move the swi h closing -position during a predetermin range of base difference between the electromotive orces of the circuits includingfiphase coincidence and to move from switch closing position when the phase difierence is"=buts1demovable circuit controlling member, means for exerting opposing torques on the mem ber; means for retarding the movement of the member to circuit controlhng. position, a cooperating movable circuit controlling member,. means for exerting opposing f-torques on said cooperatin rmember quickin accordance with the sum of.and difference lyto'move and. hold itju circuit-controlling position when one of the torques exceeds the other by a predetermined amount andquick- 1y {tbmove "said" cooperating member. from circuit controlling position when the other torqueexceeds the first torque by a predetermined amount.

16.- A synchronizing device plurality .ofcoo rating relays, eac havin an induction sk adapted tobe actuate between two electromotiveforces, contacts controlled by said disks and means for. retarding the movement of one of said disks.

17 In combination with two alternating current circuits, switching means for con necting said. circuitsand means for control control circuit, a relag the-phase relation lin said switching means comprising a control, circuit, a plurality of eontactsin the connected and arin accordance with tween the electromotive forces of said circuits for maintaining one ranged to be ener in switch operating determined range 0 com risin a.

of as contacts closed'durin'g a' prcdeta'- mined range of phase difierence between the electromotive forces and a relay connected ,and arranged to be energized in accordance with the phase relation between said electromotive forces for closing another of said contacts during another predetermined range of phase difl'erence. a

18. In combination with two alternating current circuits and-means for controlling the inter-connection of said circuits, a con trol circuit, means connected and arranged toxbe energized in accordance with the phase :relation'bet-ween the electromotive forces of said alternating current circuits operable efli'ect a connection In the control circuit only during a limited range of phase difier,

ence betweenelectromotive forces when the difference between their frequencies is lea than a predetermined value, and means reonsive to the phase relation between'said s 'elhctromotive forcesoperable within said range to control another connection in 'the control circuit.

19. In combination with two alternating current circuits and a switch for connecting the circuits, means for controlling the operation of said switch comprising a movable" member, and means connected and arranged to be energized in accordance with the phase relationbetween the electromotive forces of said circuits for maintaining said member position during a pre- ,phase difference between said electromotive forces, and means connected and arranged to be ener ized in accordance withthe phase relation tween said electromotive forces operative in response to a difierent predetermined phase relation to limit the o eration ofsaid switch to a portion of sai first predetermined range. a

20. In combination with. two alternating current circuits and a switch for connecting the circuits means for controlling the closing of said switch comprising a movable member, and means connected and arranged to be energized in accordance with the phase relation betweeuthe electromotive forces of said circuitsfor-smaintainin said member in switch-closingposition uring a predetermined range of phase difference between said electromotive forces, and means. -for'l i m1t1ng the closing of said switch to a portion of said bpredetermined range comprising a mova e member and actuating means connected and arranged to be enerzed in accordance with the phase relation tween said electromotive forces for moving the member to switch closin sition during a difierent range'of phase %i In witness whereof, I have -her'eunto' set my hand this 16th day of November, 1927.

oLIvaa c. maven.

erenc'e. 

